ManyToMany Refresh JoinedTable

kb80 · **Joined:** Sat Sep 03, 2005 9:17 am **Posts:** 2

Hibernate version:3.1

Run code:

Code:

Session s =userDAO.openSession();
User user = userDAO.findByUserIdn(username, s);
.....
s.close();




class User {
...
      @ManyToMany(cascade = CascadeType.PERSIST, fetch = FetchType.EAGER)
   @JoinTable(table = @Table(name = "userspermissiongroups"), joinColumns = @JoinColumn(name = "userId"), inverseJoinColumns = @JoinColumn(name = "permissionsGroupId"))
   public java.util.Collection<PermissionsGroup> getPermissionsGroups() {
      if (permissionsGroups == null)
         permissionsGroups = new java.util.HashSet<PermissionsGroup>();
      return permissionsGroups;
   }

....
}

When i run this code
Hibernate always refresh tables:
userspermissionsgroup.
Hibernate try delete records in table userspermissionsgroup:
and next try to insert the same records to this table:
This is sql requests:
delete from userspermissiongroups where userId=?
insert into userspermissiongroups (userId, permissionsGroupId) values(?,?)

Why he do it?

Thanks Konrad?

emmanuel · **Posted:** Fri Sep 09, 2005 6:10 am

because it's a Collection, hence have a bag semantic, hence the collections elements can be duplicated and have no PK.

You probably need a Set